Improvement in hot-air engines



UNITED ,STATES PATENT OEEICEO S. Tr. EorEE, or EOXBUEY, MASSAcHUSETTS, ASSTeNoE To ELMEE TOWNSEND.

IMPROVEMENT IN HOT-AIR ENGINES.

Specication forming part of Letters Patent No. 55,428, dated June 5, 1866.

To all whom it may concern:

Be it known that I, S. H. ROPER, ot' Rox bury, inthe county ot' Norfolk and State of Massachusetts, have invented an Improvement in Calorie Engines; and I do hereby declare that the following, taken in connection with the drawings which accompany and form part of this specification, is a description of my invention suicient to enable those skilled in the art to practice it.

In that variety of caloric engine in which cold air is supplied by a pump to the fire-box, and thence passes with the gaseous products ot' combustion to the engine-cylinder, and in which variety ot' engine the speed of the piston therein is regulated by a valve in the pipe which supplies the cylinder from the upper part of the tire-box, said valve being operated by a governor, two practical difculties arise, which it is the object of this invention to obviate. Said diculties are these: First, as the regulator-valve in the supply-pipe is closed by the action of the governor to check the speed ot' the engine the air-pump continues to work and to torce and condense air into the tire-box and the passages and chambers about the tirebox and communicating with the pump, and thus the pressure may increase till some ofthe parts are ruptured or made to leak; second, the inletyalve, which controls the periods otl admission of the vimpelling medium into the engine-cylinder, becomes ver much heated at those times when the engine runs above speed requiring the action of the regulator-valve. Hence it is desirable to make provision which will relieve the pressure accumulating when the engine is throttled, and in such a manner as to cool the inlet-valve, and it is in such provision that my invention consists.

The drawing illustrating my invention is a section taken through the firebox, the cylinder, the valve-chests, and conducting-pipes of one of my engines, with the addition thereunto of the matter embodying my present inventi'on.

a is the fire-box; b, the elongated piston in the cylinder; c, the inlet-valve; d, the exhaust valve; e, the inlet-pipe communicating with the re-box and the inlet-valve chest f, and g is the regulator-valve.

From the space h, which communicates with the passage i, leading from the air-pump, there is a pipe, j, communicating' with the inlet-valve chest j' through the automatieally-operating valve lr. rlhis valve is arranged with a sprin g, l, against which the screw m can be operated, so that the valve will yield at any desired pressure to let the comparatively cool compressed air from the pump and in the passages t and 'i pass into the inlet-valve chamberfwhenever the pressure exerted against the valve in pipe j is sutiieient to compress the spring Z.

When the valve 7c is so opened it is manifest that the valve-chest fwill be tilled with comparatively cool air, which will cool the valve c and its seat, and will, whenever valve c opens, enter the engine-cylinder, and to the extent of its expansive power propel the piston b.

It is also manifest that so long as the throttle-valve g remains open the valve k will remain closed, as the air from the pump will flow into the engine-cylinder through the passage offering least resistance, but when the throttle is closed valve 7c operates as a Safetyvalve, and relieves the ease and Iair passages from dangerous accumulation of pressure, cooling the inlet-valve c at the same time.

When my engine, arranged as described, has a considerable portion of its work thrown oft', so as to call for the action of the regulator-valve, it will be obvious that the pressure stored up in the passages to the pump and around and in the tirebox, limited to a safe degree by the action ot' the safety-valve, will be at once available to keep the normal speed ot' the engine when its maximum ot' work is again applied, differing in this respect from other caloric engines, where the speed is reduced by reduction ot' the pressure ot' the impelling medium, and in which the governor operates a regulator-valve to let the generated pressure escape from the engine and thus become wasted.

I claim- Providing the auxiliary air-passage j with the safety-valve h, when arranged to operate substantially as described, and in combination with the inlet-pipe e and its throttle-valve g.

" S. H. ROPER.

Witnesses:

J. B. CROSBY, F. GoULD, 

